1,243 research outputs found
An Investigation of The Iodine Derivatives of Certain Meta-Substituted Phenols
The purpose of this investigation was to prepare a series of iodinated meta-substituted phenols, and, if time permitted, to determine the structures of the compounds prepared. The situation was complicated somewhat by the prevailing controversy regarding the mechanism of iodination of phenols and the uncertainty involved in controlling iodine substitution in the aromatic nucleus
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Rational Design of Pore Size and Functionality in a Series of Isoreticular Zwitterionic Metal-Organic Frameworks
The isoreticular expansion and functionalization of charged-polarized porosity has been systematically explored by the rational design of 11 isostructural zwitterionic metal-organic frameworks (ZW-MOFs). This extended series of general structural composition {[M3F(L1)3(L2)1.5]·guests}n was prepared by employing the solvothermal reaction of Co and Ni tetrafluoroborates with a binary ligand system composed of zwitterionic pyridinium derivatives and traditional functionalized ditopic carboxylate auxiliary ligands (HL1·Cl = 1-(4-carboxyphenyl)-4,4′-bipyridinium chloride, Hcpb·Cl; or 1-(4-carboxyphenyl-3-hydroxyphenyl)-4,4′-bipyridinium chloride, Hchpb·Cl; and H2L2 = benzene-1,4-dicarboxylic acid, H2bdc; 2-aminobenzene-1,4-dicarboxylic acid, H2abdc; 2,5-dihydroxy-1,4-benzenedicarboxylic acid, H2dhbdc; biphenyl-4,4′-dicarboxylic acid, H2bpdc; or stilbene-4,4′-dicarboxylic acid, H2sdc). Single-crystal structure analyses revealed cubic crystal symmetry (I-43m, a = 31-36 Å) with a 3D pore system of significant void space (73-81%). The pore system features three types of pores being systematically tunable in size ranging from 17.4 to 18.8 Å (pore I), 8.2 to 12.8 Å (pore II), and 4.8 to 10.4 Å (pore III) by the choice of auxiliary ligands. All members of this series have noninterpenetrating structures and exhibit robust architectures, as evidenced by their permanent porosity and high thermal stability (up to 300 °C). The structural integrity and specific surface areas could be systematically optimized using supercritical CO2 exchange methods for framework activation resulting in BET surface areas ranging from 1250 to 2250 m2/g. Most interestingly, as a structural landmark, we found the pore surfaces lined with charge gradients employed by the pyridinium ligands. This key feature results in significant adsorption of carbon dioxide and methane which is attributed to polarization effects. With this contribution we pioneer the reticulation of pyridinium building blocks into extended zwitterionic networks in which specific properties can be targeted
Differential processing of risk and reward in delinquent and non-delinquent youth
The present study examined the behavioral and neural differences in risky decision-making between delinquent (n = 23) and non-delinquent (n = 27) youth ages 13-17 years (M = 16, SD = 0.97) in relation to reward processing. While undergoing functional neuroimaging, participants completed an experimental risk task wherein they received feedback about the riskiness of their behavior in the form of facial expressions that morphed from happy to angry. Behavioral results indicated that delinquent youth took fewer risks and earned fewer rewards on the task than non-delinquent youth. Results from whole-brain analyses indicated no group differences in sensitivity to punishments (i.e. angry faces), but instead showed that delinquent youth evinced greater neural tracking of reward outcomes (i.e. cash-ins) in regions including the ventral striatum and inferior frontal gyrus. While behavioral results show that delinquent youth were more risk-averse, the neural results indicated that delinquent youth were also more reward-driven, potentially suggesting a preference for immediate rewards. Results offer important insights into differential decision-making processes between delinquent and non-delinquent youth
In Vitro Model of Essential Fatty Acid Deficiency
The polyunsaturated fatty acids linoleic acid (18:2, n-6) and arachidonic acid (20:4, n-6) are essential for normal skin function and structure, both as eicosanoid precursors and as components of lipids forming cell membranes. Adult human keratinocytes grow optimally in serum-free medium (MCDB 153) that contains no fatty acids. These keratinocytes expand rapidly and produce normal epidermis upon in vivo grafting. Analysis of lipid extracts of epidermis and of cultured keratinocytes was done to determine the fatty acid composition of cells grown in essential fatty acid (EFA) – deficient medium. Gas chromatography and high-performance liquid chromatography analyses were done of the fatty acids in the entire cell and in a thin-layer chromatography separated fraction containing those lipids that form cellular membranes. Comparison of snap-frozen epidermis and epidermal basal cell suspensions to passage 1 to 4 cultures shows that the cells are in an extreme essential fatty acid-deficient state by the first passage. The amount of the saturated fatty adds 16:0, 18:0, and 14:0 is unchanged by culture. The polyunsaturated fatty acids are found to be significantly decreased, the cells balancing their lack with a significant increase in the relative abundance of the monounsaturated fatty acids, 18:1 and 16:1. Greater than 85–90% of the fatty acids was found in lipids associated with membranes and no unusual fatty acids were detected. Because the serum-free medium is fatty acid free and the cells cannot synthesize essential fatty acids, the rapid division of the cells results in the predominance of an extreme EFA-deficient cell type. The essential fatty acid – deficient keratinocyte is an excellent adult, normal epidermal cell model that can be used to study EFA deficiency and the effect of the eicosanoid and fatty acids on cell function and structure
Determination of acute oral toxicity of flumethrin in honey bees
Flumethrin is one of many pesticides used for the control and treatment of varroatosis in honey bees and for the control of mosquitoes and ticks in the environment. For the control of varroatosis, flumethrin is applied to hives formulated as a plastic strip for several weeks. During this time, honey bees are treated topically with flumethrin, and hive products may accumulate the pesticide. Honey bees may indirectly ingest flumethrin through hygienic behaviors during the application period and receive low doses of flumethrin through comb wax remodeling after the application period. The goal of our study was to determine the acute oral toxicity of flumethrin and observe the acute effects on motor coordination in honey bees (Apis mellifera anatoliaca). Six doses (between 0.125 and 4.000 mu g per bee) in a geometric series were studied. The acute oral LD50 of flumethrin was determined to be 0.527 and 0.178 mu g per bee (n = 210, 95% CI) for 24 and 48 h, respectively. Orally administered flumethrin is highly toxic to honey bees. Oral flumethrin disrupted the motor coordination of honey bees. Honey bees that ingested flumethrin exhibited convulsions in the antennae, legs, and wings at low doses. At higher doses, partial and total paralysis in the antennae, legs, wings, proboscises, bodies, and twitches in the antennae and legs were observed.National Science Foundation (NSF) - 0851651Uludağ Üniversitesi AGA
Identification, cloning, expression and functional interrogation of the biosynthetic pathway of the polychlorinated triphenyls ambigol A-C fromFischerella ambigua108b
The terrestrial cyanobacteriumFischerella ambigua108b produces the three polychlorinated triphenyls ambigol A-C that exhibit interesting antimicrobial, antiviral and cytotoxic activities. They are structurally related to polybrominated diphenylethers synthesized by diverse marine bacteria that are known to be highly toxic and are bioaccumulating in natural food webs. All ambigols display unusual connectivities: Ambigols A and B exhibit chlorination and ambigol C biaryl-ether bonds in the relativemetaposition at the central phenol unit, which is flanked by two 2,4-dichlorophenol units in all three compounds. Here we report on the identification of the biosynthetic gene cluster (BGC) reponsible for ambigol production inF. ambigua. After bioinformatic discovery of a putative ambigol BGC (ab) containing 10 genes, we cloned and heterologously expressed this cluster inSynechococcus elongatusPCC 7942 using Direct Pathway Cloning (DiPaC).In vivoandin vitrocharacterization of the two cytochrome P450 enzymes present in theabBGC revealed complementary selectivity for either biaryl-ether bond (Ab2) or biaryl formation (Ab3) and provided a biosynthetic route to the ambigols
Genetic Population Structure Analysis in New Hampshire Reveals Eastern European Ancestry
Genetic structure due to ancestry has been well documented among many divergent human populations. However, the ability to associate ancestry with genetic substructure without using supervised clustering has not been explored in more presumably homogeneous and admixed US populations. The goal of this study was to determine if genetic structure could be detected in a United States population from a single state where the individuals have mixed European ancestry. Using Bayesian clustering with a set of 960 single nucleotide polymorphisms (SNPs) we found evidence of population stratification in 864 individuals from New Hampshire that can be used to differentiate the population into six distinct genetic subgroups. We then correlated self-reported ancestry of the individuals with the Bayesian clustering results. Finnish and Russian/Polish/ Lithuanian ancestries were most notably found to be associated with genetic substructure. The ancestral results were further explained and substantiated using New Hampshire census data from 1870 to 1930 when the largest waves of European immigrants came to the area. We also discerned distinct patterns of linkage disequilibrium (LD) between the genetic groups in the growth hormone receptor gene (GHR). To our knowledge, this is the first time such an investigation has uncovered a strong link between genetic structure and ancestry in what would otherwise be considered a homogenous US population
Pancreatitis-diabetes-pancreatic cancer: summary of an NIDDK-NCI workshop
A workshop sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the National Cancer Institute (NCI) on "Pancreatitis-Diabetes-Pancreatic Cancer" focused on the risk factors of chronic pancreatitis (CP) and diabetes mellitus (DM) on the development of pancreatic ductal adenocarcinoma (PDAC). Sessions were held on (a) an overview of the problem of PDAC; (b) CP as a risk factor of PDAC; (c) DM as a risk factor of PDAC; (d) pancreatogenic, or type 3c, DM; (e) genomic associations of CP, DM, and PDAC; (f) surveillance of high-risk populations and early detection of PDAC; and (g) effects of DM treatment on PDAC. Recent data and current understandings of the mechanisms of CP- and DM-associated factors on PDAC development were discussed, and a detailed review of the possible risks of DM treatment on the development of PDAC was provided by representatives from academia, industry, and the Food and Drug Administration. The current status of possible biomarkers of PDAC and surveillance strategies for high-risk populations were discussed, and the gaps in knowledge and opportunities for further research were elucidated. A broad spectrum of expertise of the speakers and the discussants provided an unusually productive workshop, the highlights of which are summarized in the accompanying article
Vapor Cloud Explosion Live Test and Data Analysis Development Program
PresentationVapor Cloud Explosions (VCE), an ever-present threat to the petroleum refining industry, create hazards to employees, equipment and production capabilities. To mitigate the effect of these hazards, effective designs for structural and non-structural components must be developed and confirmed via experimental validation to ensure the safety and performance of the facility and its occupants. Current methodologies for full-scale VCE performance testing involve the use of large quantities of high explosives set at a large standoff distance to achieve the time durations common in VCE events. While effective in achieving the peak pressures involved, these tests do not adequately characterize the full behavior of the time-dependent loading conditions and other effects seen in VCE events, such as enhanced turbulence, degree of confinement and the reactivity of unburned materials. The explosive testing community recognizes that current testing methods do not fully characterize the loading behavior and that only a small number of large- scale VCE tests have been conducted by various commercial and government agencies. Unfortunately, most of the work has been in support of counterterrorism efforts, making the test data unavailable to the petroleum industry
Pancreatitis and pancreatic cancer in two large pooled case–control studies
The association between duration of pancreatitis and pancreatic cancer has not been well characterized in large population-based studies. We conducted detailed analyses to determine the association between pancreatitis onset and pancreatic cancer risk.
Data from two case–control studies of pancreatic cancer (n = 4515) in the San Francisco Bay Area and the M.D. Anderson Cancer Center were pooled for analysis (1,663 cases, 2,852 frequency-matched controls). Adjusted odds ratios (OR) were estimated using a random-effects model.
In the pooled multivariable model, history of pancreatitis was associated with a 7.2-fold increased risk estimate for pancreatic cancer [95% confidence interval (CI): 4.0, 13]. The risk estimate was nearly 10-fold in participants aged <55 years (OR = 9.9, 95% CI: 3.5, 28). A shorter temporal history of pancreatitis was more closely associated with pancreatic cancer than was a longer temporal history: <3 years (OR = 29, 95% CI: 12, 71), 3–10 years (OR = 2.6, 95% CI: 1.5, 5.6), and >10 years (OR = 1.8, 95% CI: 0.7, 4.5, p
trend < 0.001).
A short temporal history of pancreatitis was highly associated with pancreatic cancer, suggesting that pancreatitis may be an early manifestation of pancreatic cancer in some individuals. Pancreatic cancer should be considered in the differential diagnosis of individuals with an episode of pancreatitis
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